Short communication: Heart rate variability, step, and rumination behavior of dairy cows milked in a rotary milking system

摘要

Step behavior, heart rate (HR), the high-frequency(HF) component of heart rate variability (HRV), theratio of the low-frequency (LF) and HF components(LF/HF ratio) as well as rumination behavior duringmilking were investigated in dairy cows milked in ahigh-capacity rotary milking system (n = 49) to studyanimals’ stress responses to the milking process. Cardiacparameters were analyzed for undisturbed standing(baseline) and for the stages of the morning, afternoon,and evening milking processes (i.e., driving animalsfrom the barn to the pre-milking holding pen, premilkingholding pen, preparation, milking, and waitingafter milking in the milking stall). During driving, HRwas greater than during all other stages. After driving,a gradual decrease in HR was observed. The HFdecreased during driving, indicating a decrease in vagaltone compared with baseline. When animals were inthe holding pen, vagal tone decreased, whereas sympathetictone increased with lower values than recordedfor baseline and driving. During preparation, HF valueswere still lower than those recorded for baseline. Therecovery of the autonomic activity was observed followingpreparation as indicated by increased HF and decreasedLF/HF ratio during milking and waiting stages.During milking, 53.1% of the animals ruminated. Thefrequency of steps was greater during preparation (3.7± 1.8 steps/min) than during milking (0.7 ± 0.4 steps/min) and waiting after milking (1.6 ± 1.0 steps/min).Our results suggest that being in the holding pen isstressful for cows; however, vagal predominance fromthe onset of milking, the low frequency of steps, andthe high prevalence of rumination during milking suggesta possible welfare benefit of the investigated rotarymilking system.